BRPI0609786A2 - NON-HALOGENED FLAME-RETARDANT POLYURETHANE COMPOSITION, NON-HALOGENED FLAME RETARDANT PACKAGING, PROCESSES FOR THE PRODUCTION OF A NON-HALOGENED FLAME-RETARDANT POLYURETHANE COMPOSITION AND FOR THE PRODUCTION OF A CONSTRUCTION OF WIRE, CABLE AND WIRE CONSTRUCTION , CONFORMED ARTICLE - Google Patents

Abstract

COMPOSITION OF NON HALOGENATED FLAME RETARDANT THERMOPLASTIC POLYURETHANE, NON HALOGENATE FLAME RETARDANT PACKAGING, PROCESSES FOR PRODUCTION OF A THERMOPLASTIC POLYURETHANE COMPOSITION OF FLOOD RETENTION AND CONTAINING AND PRODUCTION , CONFORMED ARTICLE. Flame retardant thermoplastic polyurethane (TPU) compositions having a flame retardant package containing an organo-phosphinate component, an organo-phosphate component, and a polyhydric alcohol are disclosed. The flame retardant components can be present in an amount of about 5 to about 40% by weight of the phosphinate compound; from about 5 to about 20% by weight of the phosphate compound, and from about 0.1 to about 15% by weight of the polyhydric alcohol, based on the total weight of the TPU composition. Processes for preparing the TPU compositions and for manufacturing coated wires and cables using the TPU compositions are disclosed. TPU compositions have excellent flame retardancy capabilities as measured by the Oxygen Limit Index test and / or UL / 94 vertical burn tests.

Description

"RETARDANT THERMOPLASTIC POLYURETHANE FLAME COMPOSITION, FLAME RETARDANT POLYURETHANE COMPOSITION, METHOD OF MAKING A RETARDANT POLYURETHANE FLAME COMPOSITION, PROCESSES FOR PRODUCTION OF A POLYURETHANE POLYURETHANE POLYURETHANE COMPOSITION CONSTRUCTION OF CABLE AND WIRE, AND ARTICLE CONFORMED "

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority for U.S. Application Serial Number 60/671009 filed April 13, 2005.

FIELD OF THE INVENTION The present invention relates to flame retardant thermoplastic polyurethane (TPU) compositions, and more particularly to flame retardant polyurethane compositions containing various non-halogenated flame retardants. TPU compositions are useful for applications where high flame performance is desired, such as wire and cable applications, blown film, molding applications, and the like. This invention also relates to processes for producing TPU compositions and processes for producing wire and cable covers.

BACKGROUND OF THE INVENTION Halogenated additives, such as those based on fluorine, chlorine, and bromine, have been used to impart flame retardant properties to TPU compositions. In recent years, certain end-use applications have been specifying halogen-free TPU compositions. This required TPU formulators to look for other flame retardants to replace previously used halogenated additives.

U.S. Patent Application Publication No. 2005/0011401 discloses an elastic floor covering material which includes a phosphinate salt or a diphosphinate salt as a flame retardant.

U.S. Patent 6,777,466 issued to Eckstein, et al. discloses the use of melamine cyanurate as the only flame retardant additive in the TPU composition.

U.S. Patent 6,547,992 issued to Schlosser et al. discloses a flame retardant combination including certain phosphinate and / or diphosphinate components and a synthetic inorganic compound and / or a mineral product. Additionally, the disclosed flame retardant combination may include nitrogen containing components.

U.S. Patent 6,365,071 issued to Jenewein et al. discloses a flame retardant combination for thermoplastic polymers including certain phosphinate and / or diphosphinate components and certain nitrogen-containing components.

U.S. Patent 6,509,401 issued to Jenewein et al. discloses a flame retardant combination including certain phosphorus-containing components and certain nitrogen-containing components for thermoplastic polymers.

U.S. Patent 6,255,371 issued to Schlosser et al. discloses a flame retardant combination including certain phosphinate and / or diphosphinate components in combination with certain melamine derived components.

U.S. Patent 6,207,736 issued to Nass et al. discloses a flame retardant combination including certain phosphinic acid salts and / or diphosphinic acid salts and certain nitrogen containing phosphate components.

There is still a need in the art for effective non-halogenated flame retardant combinations which impart flame retardant characteristics to polyurethane thermoplastic compositions without impairing mechanical strength and processability.

SUMMARY OF THE INVENTION An object of an exemplary embodiment is to provide a non-halogenated flame retardant TPU composition that provides the desired flame retardant capabilities while having acceptable mechanical and processing properties.

One object of an exemplary embodiment is to provide a TPU composition that can be used as a covering for coated wires and cables.

An object of an exemplary embodiment is to provide a process for preparing a TPU composition that is suitable for flame retardant coating on coated wires and cables.

One object of an exemplary embodiment is to provide a flame retardant package for use with thermoplastic polyurethanes.

One object of an exemplary embodiment is to provide a method for rendering a flame retardant thermoplastic polyurethane composition.

One object of an exemplary embodiment is to provide wire and cable coverage using a flame retardant TPU composition.

In one aspect of the invention, a thermoplastic polyurethane (TPU) composition is provided. The composition includes at least one thermoplastic polyurethane polymer and a flame retardant package.

In one aspect, the composition includes at least one thermoplastic polyurethane and from about 5 to about 40% by weight of the Exolit® OP 1311 phosphinate proprietary compound; from about 5 to about 20% by weight of the proprietary halogen-free flame retardant phosphate-type compound NcendX® P-30; and from about 0.1 to about 15 wt% dipentaerythritol, wherein the weight percentages are based on the total weight of the thermoplastic polyurethane composition. The composition may additionally include from about 0 to about 10% by weight of ammonium pentaborate or zinc borate.

In another aspect, the thermoplastic polyurethane polymer is selected from polyester polyurethane, polyether polyurethane, polycarethane polyurethane and combinations thereof.

In another aspect, the composition includes from about 0 to about 5% by weight of an inorganic flame retardant component such as talc, ammonium phosphate, ammonium polyphosphate, calcium carbonate, antimony oxide, clay, montmorillonite clay, and your mixtures.

In another aspect the composition includes, as organic flame retardant components, a phosphinate compound, a phosphate based flame retardant compound, and a polyhydric alcohol.

In another aspect, the flame retardant additive package includes three non-halogenated flame retardant components, wherein the flame retardant additive package is present in an amount sufficient to impart at least one predetermined flame retardant characteristic to the polyurethane composition. thermoplastic.

In another aspect, the predetermined flame retardant characteristic is an oxygen limit index of at least about 35 measured according to ASTM D-2863.

In another aspect, the predetermined flame retardant characteristic is a degree of VO flammability at a thickness of about 75 mils (1.90 mm) measured according to the Underwriters Laboratory (UL 94) vertical flammability test (Standard 94). ). In another aspect, the

r

The default flame retardant characteristic is a Limited Oxygen Index (LOI) of at least 35 for compositions useful for covering wire and cable in accordance with applicable standards such as UL 1581, UL 1666, CSA FT-I, FT-4, UL 1685, IEEE 1202, IEC 332-3, and the like.

In another aspect, the flame retardant package includes a phosphinate based flame retardant and a polyhydric alcohol. The flame retardant package may further include an inorganic flame retardant component.

In another aspect, in a method of transforming a flame retardant thermoplastic polyurethane composition, a flame retardant package is used in an amount sufficient to impart at least one predetermined flame retardant characteristic to the thermoplastic polyurethane composition.

In another aspect, thermoplastic polyurethane ingredients including a polymeric intermediate selected from hydroxyl terminated polyester, hydroxyl terminated polyether, hydroxyl terminated polycarbonate, and mixtures thereof; a polyisocyanate and a chain extender are mixed in a mixing device capable of shear mixing the polyurethane ingredients. A flame retardant package is added to the mixing device, and the flame retardant additive package includes Exolit® OP 1311, a proprietary phosphinate and dipentaerythritol based additive.

In another aspect, a cable or wire construction is produced by extruding an insulating layer of a nonconductive polymeric material onto at least one metal conductor; and extruding a flame retardant cover to cover the insulated metal conductor. The cover is a thermoplastic polyurethane composition containing at least one thermoplastic polyurethane polymer; from about 5 to about 40% by weight of a first non-halogenated organic flame retardant component including a phosphinate compound; from about 5 to about 20% by weight of a second non-halogenated organic flame retardant component including a phosphate-based flame retardant, and from about 0.1 to about 15% by weight of a third non-halogenated organic flame retardant component. non-halogenated organic flame selected from pentaerythritol and dipentaerythritol based on the total weight of the thermoplastic polyurethane composition. The composition may additionally include from about 0 to about 10% by weight of ammonium pentaborate or zinc borate.

DETAILED DESCRIPTION OF THE INVENTION

The thermoplastic polyurethane (TPU) compositions of the present invention include at least one TPU polymer together with flame retardant additives.

The type of TPU polymer used in this invention may be any conventional TPU polymer that is known in the art and literature as long as the TPU polymer is capable of imparting the desired mechanical and physical properties to the flame retardant final composition.

Embodiments of the invention include adding certain flame retardant components to the TPU polymer to obtain the desired flame retardant properties of the TPU composition. Of particular interest are flame retardant organic components including a phosphate compound based on an organic salt of phosphinic acid. Organic phosphates are a recent addition to the sphere of flame retardants used in thermoplastic engineering. A preferred phosphinate is marketed as the proprietary Exolit® OP 1311 compound available from Clariant GmbH, Germany. An organic phosphinate is used in conjunction with other flame retardants in an exemplary embodiment of the flame retardant package. The phosphinate compound may be present in an exemplary embodiment of the flame retardant TPU composition in an amount of from about 5 to about 40 wt%, more preferably from about 15 to about 25 wt%, based on the total weight of the TPU composition.

Other flame retardant organic components include organic phosphates such as triaryl phosphates, and preferably a triphenyl phosphate, and more preferably a proprietary phosphorus based flame retardant, namely NcendX® P-30 from Albermarle Corporation. Organic phosphate may be present in an exemplary embodiment and an amount of from about 5 to about 20% by weight, more preferably from about 5 to about 10% by weight, based on the total weight of the composition. TPU.

Other flame retardant organic components include polyhydric alcohols such as pentaerythritol and dipentaerythritol. The polyhydric alcohol may be present in an exemplary embodiment and an amount of from about 0.1 to about 15% by weight, more preferably from about 2.5 to about 10% by weight, based on weight. total TPU composition. The composition may additionally include from about 0 to about 10% by weight of ammonium pentaborate or zinc borate.

In addition, various conventional inorganic flame retardant components may be employed in the TPU flame retardant composition. Suitable inorganic flame retardants include any of those skilled in the art, such as ammonium phosphate, ammonium polyphosphate, calcium carbonate, antimony oxide, and clay, including montmorillonite clay which is often referred to as nano-clay. Inorganic flame retardants may be used at a level of 0 to about 5% by weight of the TPU composition. Preferably, inorganic flame retardants are not present and the composition includes only TPU and the flame retardant organic components.

Thus, in an exemplary embodiment, a flame retardant thermoplastic polyurethane composition includes at least one thermoplastic polyurethane polymer and a flame retardant package including an organic phosphinate compound, an organic phosphate compound, and a polyhydric alcohol. In other exemplary embodiments, inorganic flame retardant fillers may be incorporated into the flame retardant package.

For some applications, auxiliary additives, which are not flame retardant per se, may be used in the TPU compositions of this invention. Additives such as colorants, antioxidants, antiozonants, light stabilizers, inert fillers, and the like may be used in amounts of 0 to 5% by weight of the TPU composition. Preferably, auxiliary additives are not present in the TPU composition.

In one embodiment, the TPU polymer may be prepared by reacting a polyisocyanate with an intermediate such as hydroxyl terminated polyester, hydroxyl terminated polyether, hydroxyl terminated polycarbonate, or mixtures thereof; with one or more chain extending glycols, all well known to those skilled in the art. U.S. Patent 6,777,466 issued to Eckstein et al. provides detailed disclosure of processes for providing certain TPU polymers which may be used in the embodiments of the present invention and is incorporated herein in its entirety.

The TPU-type polymer used in this invention may be any conventional TPU polymer that is known in the art and literature, provided that the TPU polymer has a suitable molecular weight. TPU polymer is generally prepared by reacting a polyisocyanate with an intermediate such as hydroxyl terminated polyester, hydroxyl terminated polyether, hydroxyl terminated polycarbonate, or mixtures thereof; with one or more chain extenders, all well known to those skilled in the art.

The hydroxyl terminated polyester intermediate is generally a linear polyester having a number average molecular weight (Mn) of from about 500 to about 10,000, desirably from about 700 to about 5,000, and preferably from about 700 to about 4000, an acid number generally less than 1.3 and preferably less than 0.8. Molecular weight is determined by terminal functional group testing and is related to numerical average molecular weight. Polymers are produced by (1) an esterification reaction of one or more glycols with one or more dicarboxylic acids or anhydrides or (2) by transesterification reaction, i.e., the reaction of one or more glycols with dicarboxylic acid esters. Molar ratios generally of more than one mol of glycol to acid are preferred in order to obtain straight chains having a preponderance of terminal hydroxyl groups. Suitable polyester intermediates also include various lactones such as polycaprolactone typically made of ε-caprolactone and a bifunctional initiator such as diethylene glycol. Dicarboxylic acids of the desired polyester may be aliphatic, cycloaliphatic, aromatic or combinations thereof. Suitable dicarboxylic acids which may be used alone or in mixtures generally have a total of 4 to 15 carbon atoms and include: succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, dodecanedioic, isophythalic, terephthalic, cyclohexane, dicarboxylic and similar . Anhydrides of the above dicarboxylic acids such as italic anhydride, tetrahydrophythalic anhydride or the like may also be used. Adipic acid is the preferred acid. Glycols which are reacted to form a desirable polyester intermediate may be aliphatic, aromatic or combinations thereof, and have a total of 2 to 12 carbon atoms, and include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1 , 3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, 1,4-cyclohexanedimethanol, decamethylene glycol, dodecamethylene glycol, and the like; 1,4-Butanediol is the preferred glycol.

Hydroxyl-terminated polyether intermediates are polyether polyols derived from a diol or polyol having a total of 2 to carbon atoms, preferably an alkyl diol or glycol which is reacted with an alkylene oxide-containing ether having 2 to 6 carbon atoms, typically ethylene oxide or propylene oxide or mixtures thereof. For example, hydroxy-functional polyether may be produced by first reacting propylene glycol with propylene oxide followed by subsequent reaction with ethylene oxide. Primary hydroxyl groups resulting from ethylene oxide are more reactive than secondary hydroxyl groups and thus preferred. Useful commercial polyester polyols include poly (ethylene glycol) ethylene glycol reacted ethylene oxide compound, poly (propylene glycol) propylene glycol reacted propylene oxide compound, poly (tetramethyl glycol) tetrahydrofuran (PTMG) reacted water compound. Polytetramethylene ether glycol (PTMEG) is the preferred polyether intermediate. Polyether polyols further include polyamide adducts of an alkylene oxide and may include, for example, ethylenediamine adduct of the propylene oxide ethylene reaction product, diethylenetriamine adduct of the propylene oxide diethylenetriamine reaction product, and polyether similar polyamide type polyols. Copolyethers may also be used in the present invention. Typical copolyethers include the reaction product of THF with ethylene oxide or THF with propylene oxide. These are available from BASF as Poly THF B, a block copolymer, and Poly THF R, a random copolymer. The various polyether intermediates generally have a number average molecular weight (Mn), determined by terminal functional group assay which is an average molecular weight of from about 500 to about 10,000, desirably from about 500 to about 5,000, and preferably from about 700 to about 3000.

The polycarbonate based polyurethane resin of this invention is prepared by reacting a diisocyanate with a combination of a hydroxyl terminated polycarbonate and a chain extender. Hydroxyl terminated polycarbonate may be prepared by reacting a glycol with a carbonate.

U.S. Patent 4,131,731 discloses hydroxyl-terminated polycarbonates and their preparation. Such polycarbonates are linear and have terminal hydroxyl groups with essential exclusion from other terminal groups. The essential reagents are glycols and carbonates. Suitable glycols are selected from aliphatic and cycloaliphatic diols containing 4 to 40, and preferably 4 to 12 carbon atoms, and polyoxyalkylene glycols containing 2 to 20 alkoxy groups per molecule with each alkoxy group containing 2 to 4 carbon atoms. Suitable diols for use in the present invention include aliphatic diols containing 4 to 12 carbon atoms such as butanediol-1,4, pentanediol-1,4, neopentyl glycol, hexanediol-1,6,2,2,4-trimethylexanediol-1,6 decanediol-1,10, hydrogenated dilinoleyl glycol, hydrogenated dioleyl glycol; and cycloaliphatic diols such as cyclohexanediol-1,3, dimethylolcyclohexane-1,4, cyclohexanediol-1,4, dimethylolcycloexane-1,3,4,4-endomethylene-2-hydroxy-5-hydroxymethyl cyclohexane, and polyalkylene glycols. The diols used in the reaction may be a single diol or a mixture of diols depending on the desired properties of the finished product.

Polycarbonate intermediates that are hydroxyl terminated are generally those known in the art and literature. Suitable carbonates are selected from alkylene carbonates composed of a 5- to 7-membered ring having the following general formula:

<formula> formula see original document page 12 </formula>

where R is a saturated divalent radical containing 2 to 6 linear carbon atoms. Suitable carbonates for use herein include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, 1,2-propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-ethylene carbonate 1,3-pentylene carbonate, 1,4-pentylene carbonate, 2,3-pentylene carbonate, and 2,4-pentylene carbonate.

In addition, dialkylcarbonates, cycloaliphatic carbonates, and diarylcarbonates are suitable herein. Dialkylcarbonates may contain 2 to 5 carbon atoms in each alkyl group and specific examples thereof are diethylcarbonate and dipropylcarbonate. Cycloaliphatic carbonates, especially dicycloaliphatic carbonates, may contain 4 to 7 carbon atoms in each cyclic structure, and there may be one or two of these structures. When one group is cycloaliphatic, the other may be alkyl or aryl. On the other hand, if one group is aryl, the other may be alkyl or cycloaliphatic. Preferred examples of diarylcarbonates, which may contain 6 to 20 carbon atoms in each aryl group, are diphenylcarbonate, ditholylcarbonate, and dinaflylcarbonate.

The reaction is carried out by reacting a glycol with a carbonate, preferably an alkylene carbonate in the 10: 1 to 1: 10 molar range, but preferably 3: 1 to 1: 3 at a temperature of 100 ° C to 300 ° C and at a pressure in the range 0.1 to 300 mm of mercury in the presence or absence of an interesterification catalyst, with distillation of low boiling glycols.

More specifically, hydroxyl terminated polycarbonates are prepared in two stages. In the first stage, a glycol is reacted with an alkylene carbonate to form a low molecular weight hydroxyl terminated polycarbonate. The low boiling glycol is distilled off at a temperature of 100 ° C to 300 ° C, preferably 150 ° C to 250 ° C, under a reduced pressure of 10 to 30 mm Hg, preferably 50 to 200 mm Hg. . A fractionation column is used to separate the glycol byproduct from the reaction mixture. The glycol by-product is removed from the top of the column and unreacted alkylene carbonate and glycol reagents are returned to the reaction vessel as reflux. An inert gas stream or inert solvent may be used to facilitate removal of the glycol byproduct as it is formed. When the amount of glycol by-product obtained indicates that the degree of polymerization of the hydroxyl terminated polycarbonate is in the range of 2 to 10, the pressure is gradually reduced to 0.1 to 10 mm Hg and the unreacted glycol and alkylene carbonate are removed. . This marks the beginning of the second reaction stage during which the low molecular weight hydroxyl terminated polycarbonate is condensed by distilling off glycol as it is formed at a temperature of from 100 ° C to 300 ° C, preferably 150 ° C. C at 250 ° C and at a pressure of 0.1 to 10 mm Hg until the desired molecular weight for hydroxyl terminated polycarbonate is obtained. Molecular weight (Mn) of hydroxyl terminated polycarbonates may range from about 500 to about 10,000, but in a preferred embodiment it will be in the range of 500 to 2500.

Suitable extender glycols (ie, chain extenders) are lower aliphatic or lower glycols having from about 2 to about 10 carbon atoms and include, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1, 4-butanediol, 1,6-hexanediol, 1,3-butanediol, 1,5-pentanediol, 1,4-cyclohexanedimethanol hydroquinone di (hydroxyethyl) ether, neopentylglycol, and the like, with 1,4-butanediol being preferred.

The desired TPU polymer used in the TPU composition of this invention is generally prepared from the above intermediates as hydroxyl terminated polyesters, polyether or polycarbonate, preferably polyether, which are further reacted with a polyisocyanate, preferably a diisocyanate, along with desirably extender glycol. in a so-called one-step process or simultaneous co-reaction of polyester, polycarbonate or polyether intermediate, diisocyanate, and glycol extender to produce a high molecular weight linear TPU polymer. The preparation of macroglycol is generally well known in the art and literature and any suitable method may be used. The weight average molecular weight (Mw) of the TPU polymer is generally about 80,000 to 800,000, and preferably about 90,000 to about 450,000 Daltons. The equivalent weight amount of diisocyanate to the total weight equivalent amount of hydroxyl containing components, i.e. hydroxyl terminated polyester, polyether or polycarbonate and glycol chain extender, is about 0.95 to about 1.10, desirably from about 0.96 to about 1.02, and preferably from about 0.97 to about 1.005. Suitable diisocyanates include aromatic diisocyanates such as: 4,4'-methylenobis- (phenyl isocyanate) (MDI); m-xylylene diisocyanate (XDI), phenylene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, diphenylmethane-3,3'-dimethoxy-4,4'-diisocyanate and toluene diisocyanate (TDI); as well as aliphatic diisocyanates such as isophorone diisocyanate (IPDI), 1,4-cyclohexyl diisocyanate (CHDI), decane-1,10-diisocyanate, and dicyclohexyl methane-4,4'-diisocyanate. The most preferred diisocyanate is 4,4'-methylenobis (phenyl isocyanate), i.e., MDI.

The desired TPU polymer used in the TPU composition is generally prepared from the above noted intermediates in a so-called one-step process or simultaneous co-reaction of polyester, polycarbonate or polyether intermediate; polyisocyanate; and chain extender to produce a high molecular weight linear TPU polymer.

In the one-step polymerization process that usually occurs in situ, a simultaneous reaction occurs between three components, that is, one or more intermediates, one or more polyisocyanates, and one or more chain extenders, with the reaction being generally started at a temperature of about 100 ° C to about 120 ° C. Since the reaction is exothermic, the reaction temperature generally increases to about 220 ° C-250 ° C. In an exemplary embodiment, the TPU polymer may be pelletized after the reaction. Flame retardant components may be incorporated with TPU polymer pellets to form a flame retardant composition in a subsequent process. The TPU polymer and flame retardant organic components may be mixed and fused together by any means known to those skilled in the art. If a pelleted TPU polymer has been used, the polymer may be melted at a temperature of about 150 ° C to 215 ° C, preferably about 160-190 ° C, and more preferably about 170-180 ° C. The particular temperature used will depend on the particular TPU polymer used, as is well understood by those skilled in the art. The TPU polymer and flame retardant components are combined to form an intimate physical mixture. Combination may occur in any commonly used mixing device capable of providing shear mixing, but a twin screw extruder having multiple thermal zones with multiple feed ports is preferably used for the combining and melting (processing) process.

TPU polymer and flame retardant components may be pre-combined prior to addition to the processing extruder or may be added or added by measuring the processing extruder at different streams and zones of the extruder.

In an alternative embodiment, the TPU polymer is not pelleted prior to the addition of flame retardant components. Instead, the process for forming a flame retardant thermoplastic polyurethane composition is a continuous process in situ. Polyurethane polymer forming ingredients are added to a reaction vessel, such as a twin screw extruder as indicated above. After formation of the thermoplastic polyurethane polymer, flame retardant components may be added or metered to the extruder at different streams and / or different zones of the extruder to form a thermoplastic polyurethane composition. The flame retardant components are added in an amount sufficient to impart at least one predetermined flame retardant characteristic to the composition as indicated in more detail below.

The resulting TPU composition may exit the extruder die in a molten state and be pelleted and stored for later use in the manufacture of finished articles. The finished articles may comprise injection molded parts, especially using polyester polyurethane based TPU compositions. Other finished articles may include extruded profiles. The TPU composition may be used as a cable sheath as indicated in more detail below.

Thermoplastic polyurethanes are generally valued in end applications because of their abrasion and wear resistance, toughness, durability and flexibility at low temperature, ease of processing, and other attributes. If additives such as flame retardants are present in a TPU composition, some reduction in the desired properties of the material may occur. The flame retardant package should thus provide the desired flame retardation without sacrificing other material properties.

One property to consider is the desired tensile strength at break of the TPU composition measured in accordance with ASTM D412. In one embodiment, the tensile strength at break is at least 1500 psi (10.34 MPa) and elongation 150%. It is also important to note that the tensile strength at failure mentioned in this disclosure is the tensile strength measured in the flame retardant TPU composition after its processing into a finished part.

The disclosed TPU compositions, due to their flame retardant properties, abrasion resistance and good tensile strength, are particularly suitable for use as a cover for electrical conductors in the manufacture of coated wire and cable. One or more insulated conductors may be coated with electrical insulation material such as fiberglass or other nonflammable textile. The conductor or conductor assembly is then coated with a cover material (i.e., a TPU composition) for protection of the electrical conductors. This cover material must be flame resistant in case of fire.

The types of coated wire and cable best suited for using a cover made of TPU compositions are detailed in UL-1581 which contains specific details of conductors, insulation, cover and other coating layers and sample preparation methods. , specimen selection, conditioning, measurement and calculation.

Fire resistance performance of a cable or wire construction can be influenced by many factors, with coverage being a factor. Flammability of insulation as well as other internal components such as paper coatings, fillers and the like may also affect the fire resistance of a cable or wire construction.

Exemplary embodiments of coated wires and cables consist of extruding a TPU composition over a set of insulated conductors to form a sheath around the insulated conductors. The thickness of the coating depends on the conditions of the desired final application. Typical cover thickness is in the range of about 0.25 to 5 mm, more typically in the range of about 0.5 mm to about 1.5 mm. The thinner cover typically has a thickness of 0.51 to 0.76 mm and therefore a minimum LOI of 35 is desirable at this thickness to make the cover suitable for use in fire-rated cable tray applications.

TPU compositions may be extruded to form the cover from a prefabricated TPU composition. Usually, the TPU composition is in the form of pellets for easy feeding into the extruder. This method is the most common because TPU composition is not usually done by the wire and cable manufacturer. However, according to an exemplary embodiment of the invention, the wire or cable cover may be extruded directly from a suitable extruder for mixing and melting without going through the separate pelletizing step of the flame retardant TPU composition.

Another property of clean TPU that can be altered by the addition of flame retardant components is processability. Thus it is advantageous to employ a flame retardant that only minimally affects processability if it does so. In this disclosure "processability" refers to two phases: the initial mixing and melting (and pelleting) of the TPU composition and the secondary processing as extrusion into a wire and cable cover. In the initial mixing and melting phase, the desired qualities refer to yarn integrity, absence of polymer residues adhering to the outer surface of the matrix, uniformity in pelletizing, and the like. In secondary processing, additional qualities such as sheet extrusion capacity, aesthetic appearance, absence of brittleness, smooth surface (no bulges or non-roughness), etc. may be desired. The surface must be uniform, ie have no raised or depressed areas greater than 0,1 mm. The extruded TPU should not have torn or protruding edges and should be able to maintain its melt strength and not foam upon release of gases. The TPU must also have a large processing temperature window. It is desirable for the temperature window to be at least 60 ° C and preferably at least 110 ° C, ie the extrusion temperature may be varied at 60 ° C or 110 ° C and the TPU composition retains good extrusion qualities. This is very important because in a large scale production environment it is difficult to maintain an exactly adjusted extrusion temperature. The above aspects define what is referred to as good processability.

A flame retardant characteristic conferred to the TPU composition may be an improved oxygen limit index (LOI). In many applications, the flame retardant TPU must meet a certain LOI standard. The LOI test was formalized as ASTM D2863. LOI is the minimum percentage of oxygen that allows the sample to maintain combustion under specified conditions similar to that of a candle, and thus can be considered as a measure of the ease of extinguishing a sample. An exemplary embodiment of the present invention provides a flame retardant TPU composition having an LOI of at least about 35. LOI results of at least 35 are very unexpected for TPU compositions, as typically the LOI is less than 30. , and more typically about 25 µm for flame retardant TPU compositions. Many users require a LOI of 35 for cables that are placed in trays in buildings and this requirement for a LOI of 35 has prevented the use of TPU in this application.

Another feature of the flame retardant is measured by the Underwriters 15 Laboratories vertical burn test (UL 94). An exemplary embodiment of the present invention provides a flame retardant TPU composition capable of obtaining a V-O rating in the UL-94 test at a thickness of about 1.90 mm. As the UL rating must always be reported with thickness, an exemplary embodiment achieves a V-O rating at a thickness of about 1.90 mm.

The invention will be better understood by reference to the following examples.

Another useful ingredient for the TPU compositions of this invention is an antioxidant such as hindered phenols and dialkylated diphenylamine. Antioxidants, if used, are used at a level of from 0.05 to 2.0 wt.%, Preferably from 0.1 to 1.0, and most preferably from 0.1 to 0.5 wt.%. based on the total weight of the TPU composition. EXAMPLES

Examples 1 and 2 are presented to show preferred non-halogenated flame retardants in a polyether TPU formulation. Examples 1 and 2 use a commercially available pellet-shaped 95 Shore A hardness TPU (Estane® 58212), which was made using a PTMEG ether intermediate, butanediol chain extender (BDO) and MDI diisocyanate. In Example 2, the three non-halogenated flame retardants used (phosphinate, phosphate and polyhydric alcohol) were added to the TPU by shear mixing the ingredients in an extruder. In Examples 1 and 3, the flame retardant phosphate, which is a liquid, was initially swollen in TPU pellets and the other ingredients were added by shear mixing in an extruder.

Example 3 is presented to show preferred non-halogenated flame retardants in a polyester TPU formulation. Polyether TPU is a commercially available TPU (Estane® X-4809) that has 5OD Shore D hardness.

Table 1 below shows in% by weight the formulations used in Examples 1-3.

Table 2 below shows the test results of the formulations of Examples 1-3.

TABLE 1

<table> table see original document page 21 </column> </row> <table>

1. Estane® 58212 Polyether TPU, Shore A 95 hardness from Noveon, Inc.

2. Estane® X-4809 TPU Polyester, Shore D 50 Hardness from Noveon, Inc.

3. Exolit® OP 1311 from Clariant GmbH

4. NcendX® P-30 from Albermarle Corporation

5. Stalite® S from Noveon, Inc.

6. Irganox® 245 from Ciba-Geigy Corp. Test results of the above compositions are shown in Table 2 below.

TABLE 2

Examples

<table> table see original document page 22 </column> </row> <table>

* indicates the property has not been tested

All three compounds showed good processability in both polymer production and compound extrusion into sheets.

Although they have been set forth in accordance with the patent statutes, the best mode and the preferred embodiment, the scope of the invention is not limited by them but by the scope of the appended claims.

Claims (34)

1. A flame retardant thermoplastic polyurethane composition, characterized in that it has good melt processing characteristics including: (a) at least one thermoplastic polyurethane polymer; (b) from about 5 to about 40% by weight of a first non-halogenated organic flame retardant component containing a phosphinate compound; (c) from about 5 to about 20% by weight of a second non-halogenated organic flame retardant component containing a phosphate compound; and (d) from about 0.1 to about 15% by weight of a third non-halogenated organic flame retardant component selected from pentaerythritol and dipentaerythritol; wherein the weight percentages are based on the total weight of the thermoplastic polyurethane composition, and wherein said flame retardant polyurethane is at a VO to 1.90 mm thickness measured according to the UL 94 vertical burn test and an Oxygen Limit index of at least about 35 measured according to ASTM D2863. The flame retardant thermoplastic polyurethane composition according to claim 1, characterized in that in (b) the phosphinate compound is present at a level of from about 15 to about 25% by weight. The flame retardant thermoplastic polyurethane composition according to claim 1, characterized in that in (c) the phosphate compound is present at a level of from about 5 to about 10% by weight. The flame retardant thermoplastic polyurethane composition according to claim 1, characterized in that in (d) the selected pentaerythritol or dipentaerythritol is present at a level of from about 2.5 to about 10% by weight. The flame retardant thermoplastic polyurethane composition according to claim 1, characterized in that in (a) the thermoplastic polyurethane polymer is selected from polyurethane polyester, polyurethane polyether, polyurethane polycarbonate, and combinations thereof. The flame retardant thermoplastic polyurethane composition according to claim 5, characterized in that in (a) the thermoplastic polyurethane polymer is polyether polyurethane. The flame retardant thermoplastic polyurethane composition according to claim 1, further comprising: (e) from about 0 to about 5% by weight of an inorganic flame retardant component based on the total weight of the thermoplastic polyurethane composition. The flame retardant thermoplastic polyurethane composition according to claim 7, characterized in that in (e) the inorganic flame retardant component, if present, is selected from talc, ammonium phosphate, ammonium polyphosphate, ammonium pentaborate. ammonium, zinc borate, calcium carbonate, antimony oxide, clay, montmorillonite clay, and mixtures thereof. 9. A flame retardant thermoplastic polyurethane composition comprising: (a) at least one thermoplastic polyurethane polymer; and (b) a flame retardant package comprising: (i) a first non-halogenated flame retardant component containing a phosphinate compound; (ii) a second non-halogenated flame retardant component containing an organic phosphate compound; and (iii) a third non-halogenated phosphate-free flame retardant component; wherein the flame retardant package is present in an amount sufficient to impart at least one predetermined flame retardant characteristic to the thermoplastic polyurethane composition. The flame retardant thermoplastic polyurethane composition according to claim 9, characterized in that the at least one predetermined flame retardant characteristic is an oxygen limit index of at least about 35 measured according to ASTM D- 2863. The flame retardant thermoplastic polyurethane composition according to claim 9, characterized in that the at least one predetermined flame retardant characteristic is a flammability degree VO at a thickness of 1.90 mm measured according to UL 94 The flame retardant thermoplastic polyurethane composition according to claim 9, characterized in that the flame retardant package additionally includes an inorganic flame retardant component. The flame retardant thermoplastic polyurethane composition according to claim 9, characterized in that in (a) the thermoplastic polyurethane polymer is selected from polyurethane polyester, polyurethane polyether, polyurethane polycarbonate, and combinations thereof. Flame retardant thermoplastic polyurethane composition according to claim 13, characterized in that in (a) the thermoplastic polyurethane polymer is polyether polyurethane. The flame retardant thermoplastic polyurethane composition of claim 9, characterized in that in (b) (iii) the third non-halogenated flame retardant compound is selected from pentaerythritol and dipentaerythritol. A flame retardant thermoplastic polyurethane composition according to claim 9, characterized in that in (b) the flame retardant package further comprises: (iv) an inorganic flame retardant component. 17. A flame retardant package comprising: (a) a first non-halogenated flame retardant component containing a phosphinate compound; (b) a second non-halogenated flame retardant component containing an organic phosphate compound; and (c) a third non-halogenated flame retardant component containing a polyhydric alcohol. The flame retardant package of claim 17, characterized in that it additionally contains: (d) an inorganic flame retardant component. Flame retardant package according to Claim 18, characterized in that the inorganic flame retardant component is selected from talc, ammonium phosphate, ammonium polyphosphate, calcium carbonate, antimony oxide, clay, montmorillonite clay. , and their mixtures. Flame retardant package according to claim 17, characterized in that in (c) the polyhydric alcohol is selected from dipentaerythritol and pentaerythritol. A method of making a flame retardant thermoplastic polyurethane composition comprising: mixing a flame retardant package comprising (a) a first non-halogenated flame retardant component containing a phosphinate compound; (b) a second non-halogenated flame retardant component containing an organic phosphate compound; and (c) a third non-halogenated flame retardant component containing a polyhydric alcohol with a thermoplastic polyurethane polymer wherein the flame retardant package is present in an amount sufficient to impart at least one predetermined flame retardant characteristic to the composition of the flame retardant. thermoplastic polyurethane. The method according to claim 21, characterized in that the at least one predetermined flame retardant characteristic includes an oxygen limit index of at least about 35 measured according to ASTM D-2863. A method according to claim 21, characterized in that the at least one predetermined flame retardant characteristic includes a flammability degree VO at a thickness of 1.90 mm measured according to UL 94. A method according to claim 21, characterized in that: the phosphinate compound is present at a level of from about -5 to about 40% by weight; the organic phosphate compound is present at a level of from about 5 to about 20% by weight; and polyhydric alcohol is present at a level of from about 0.1 to about 15% by weight; wherein the weight percentages are based on the total weight of the thermoplastic polyurethane composition. A method according to claim 24, characterized in that the flame retardant package further comprises an inorganic flame retardant component present at a level of from about 0 to about 5% by weight based on the total weight of the flame retardant. thermoplastic polyurethane composition. Method according to claim 21, characterized in that the mixing is carried out in a twin screw extruder. Method according to claim 26, characterized in that the thermoplastic polyurethane composition is pelletized after mixing. A process for producing a flame retardant thermoplastic polyurethane composition comprising: a) mixing thermoplastic polyurethane ingredients comprising a polymeric intermediate selected from hydroxyl terminated polyester, hydroxyl terminated polyether, hydroxyl terminated polycarbonate, and mixtures thereof, a polyisocyanate, and a chain extender in a mixing device capable of shear mixing thermoplastic polyurethane ingredients; (b) after (a) adding a flame retardant package to the mixing device, the flame retardant package comprising a first non-halogenated flame retardant component containing a phosphinate compound present at a level of about 5 to about 40 wt%; a second non-halogenated flame retardant component comprising a phosphate compound present at a level of from about 5 to about 20% by weight; and a third non-halogenated flame retardant component selected from pentaerythritol and dipentaerythritol present at a level of from about 0.1 to about 15% by weight, wherein the weight percentages are based on the total weight of the thermoplastic polyurethane retardant composition. flame. A process for producing a cable and wire construction, comprising: (a) extruding an insulating layer of a nonconductive polymer material onto at least one metal conductor; and (b) extruding a flame retardant cover to cover at least one insulated metal conductor; wherein the cover is a thermoplastic polyurethane composition comprising: (i) at least one thermoplastic polyurethane polymer; (ii) from about 5 to about 40% by weight of a first non-halogenated organic flame retardant component containing a phosphinate compound; (iii) from about 5 to about 20% by weight of a second non-halogenated organic flame retardant component containing a phosphate compound; and (iv) from about 0.1 to about 15% by weight of a third nonhalogenated organic flame retardant component containing dipentaerythritol; wherein the weight percentages are based on the total weight of the thermoplastic polyurethane composition. 30. Cable and wire construction, characterized in that it comprises: (a) at least one metal conductor wherein said conductor is insulated with a non-conductive polymeric material; and (b) a flame retardant cover covering said at least one insulated metal conductor, wherein said cover is a thermoplastic polyurethane composition containing: (i) at least one thermoplastic polyurethane polymer; (ii) from about 5 to about 40% by weight of a non-halogenated first organic flame retardant component including a phosphinate compound; (iii) from about 5 to about 20% by weight of a second non-halogenated organic flame retardant component containing a phosphate compound; and (iv) from about 0.1 to about 15% by weight of a third non halogenated organic flame retardant component containing dipentaerythritol; wherein weight percentages are based on the total weight of the thermoplastic polyurethane composition A shaped article, characterized in that it comprises a flame retardant thermoplastic polyurethane composition, wherein the composition includes: (a) at least one thermoplastic polyurethane polymer; (b) from about 5 to about 40% by weight of a first non-halogenated organic flame retardant component containing a phosphinate compound; (c) from about 5 to about 20% by weight of a second non-halogenated organic flame retardant component containing a phosphate compound; and (d) from about 0.1 to about 15% by weight of a third non-halogenated organic flame retardant component selected from pentaerythritol and dipentaerythritol; wherein the weight percentages are based on the total weight of the thermoplastic polyurethane composition. 32. Flame retardant thermoplastic polyurethane composition, characterized in that it consists essentially of: (a) at least one polyether-based thermoplastic polyurethane polymer; (b) about 15 to about 25% by weight of a first non-halogenated organic flame retardant component containing a phosphinate compound; (c) about 5 to about 10% by weight of a second non-halogenated organic flame retardant component containing a phosphate compound; and (d) about 2.5 to about 10% by weight of a third non-halogenated organic flame retardant component including dipentaerythritol; and (e) about 0 to about 5% by weight of a talc-containing inorganic flame retardant component; wherein the weight percentages are based on the total weight of the thermoplastic polyurethane composition. The flame retardant thermoplastic polyurethane composition according to claim 1, further comprising from about 0.05 to about 2.0% by weight of antioxidant. The flame retardant thermoplastic polyurethane composition according to claim 33, characterized in that said antioxidant is selected from hindered phenols and dialkylated diphenylamine, and mixtures thereof.